Impact forces are used to simulate the collision between two parts. As two parts approach within a specified distance, the impact force becomes active, and a force specified by the impact parameters is applied to both of the colliding parts.
An impact force is controlled by the following parameters:
Distance: The distance from the contact point on the first link to the force action point on the first part (the point that was graphically identified); for example, a sphere of radius <distance> centered at the action point of the force. During the simulation, when the distance between the impact point on the second part is equal to this parameter, then impact occurs.
Stiffness: This is the stiffness of the boundary interaction between the two parts. It should be set to a number that approximates the material stiffness of the two parts in collision.
Exponent: The exponent of the force deformation characteristic. COSMOSMotion models the collision using an exponential force function.
Max Damping: The maximum damping coefficient of the boundary interaction.
Penetration: The boundary penetration distance where full damping occurs.
When the distance between the points is reached and the impact force becomes active, it produces a force that is a function of the relative velocity of the two parts to which the force is attached. The following graph shows an example:
To create an impact force:
Display the Impact Dialog box using one of the following methods:
From the Motion menu, point to Forces and then select Impact.
Right-click the Forces branch in the Browser, and then select Add Impact Force.
Right-click the Springs branch in the Browser, and then select Add Impact Force.
Right-click one or two moving or ground parts, and then select Forces Add Impact Force.
If not already selected, select the Definition tab.
Select the components to which the force is going to be applied.
In the first Select Location text box, select a vertex, circular edge, or linear edge on each component to define the points at which the force is applied.
Select
the points in the same order as you selected the components. Verify that
the first point that you select belongs to the first component selected
and the second point belongs to the second component selected. If you
select the points in the opposite order as the components, your mechanism
may not behave properly.
In the Stiffness text box, enter the impact value.
Select the Design button to define the impact distance of the force. If you set Design to on, the impact distance is automatically defined to be the distance between the two points that you selected in the Points dialog box.
Select Apply to create the impact force and close the dialog box.